Glendale, Arizona-- A couple's $5 purchase of a horse picture at a yard sale uncovered a hidden treasure.

CBS Affiliate KPHO reports that Pam Dwyer and her husband picked up a horse picture at a yard sale in Sun City. But Dwyer said her husband had a hunch that's not all they were getting.

As he examined the frame, he said, "I just have this gut feeling that there's something behind that," she recalled.

When they removed the horse picture from the frame, they found an exceptional portrait of former President John F. Kennedy dating from 1961.

"I was just in awe of the detail, and the likeness, and that it was an original," Dwyer said.

She did research on the artist, Carmelo Soraci, and found out he was an infamous forger who served time. But while incarcerated, he unleashed a hidden talent.

"He was best known for the stained glass artwork he created when he was in prison," Dwyer said.

Dwyer took her find to art appraiser Lisa Barnes, who works in Anthem, Ariz. She admitted garage sale finds are "hit-and-miss," and noted that Soraci (who was in Sing Sing and Donnamora Prisons in New York in the 1940s and '50s, and later wrote the book "The Convict and the Stained Glass Windows") "doesn't have a history of sales."

Because of that, she said it is tough give an exact appraisal, but the quality may speak for itself; Barnes appraised the portrait at $2,500 to $5,000.

"Someone like the Smithsonian would buy this because of the merit of how he captured and depicted JFK," she said.

Dwyer was happy with how much Barnes was impressed by the artwork, and told KPHO that she'll likely part with a portrait worth more than just a thousand words.